The gap between abstraction levels in analog design is a major obstacle for advancing, implementing and verifying analog and mixed-signal integrated circuit design. In order to achieve high performance and high yield, mixed-signal system components or analog blocks must be optimized at both system and circuit levels. For a top-down design approach, this process starts with designing and optimizing the system with block or component models at high levels of abstraction. The specifications for each block that lead to the best system performance are then obtained. Each sub-block is then designed and optimized toward these specifications. The issue with this approach is that generating an accurate model, if it is even feasible, takes significant effort. Therefore, some important characteristics of the blocks are ignored at the high-level simulations, which makes the obtained sub-block specifications less reliable and less accurate.